The present disclosure relates to a vehicle seat sliding device.
A vehicle seat sliding device disclosed in Japanese Unexamined Patent Application Publication No. 2010-036609 (Patent Document 1) comprises a lower rail and an upper rail. The lower rail is provided on a floor of a vehicle. The upper rail is slidably engaged with the lower rail. The upper rail is mounted to a seat.
The upper rail comprises a rolling element capable of rolling. An outer circumferential surface of the rolling element contacts the lower rail. When the upper rail slides with respect to the lower rail, the rolling element rolls.
In a vicinity of the rolling element in the upper rail, a concave stepped portion is provided. A bearing portion made of resin is mounted to the concave stepped portion. The bearing portion is slidable in the concave stepped portion in a longitudinal direction of the upper rail. When sliding in the concave stepped portion in a first direction, the bearing portion contacts the rolling element. When sliding in the concave stepped portion in a second direction opposite to the first direction, the bearing portion recedes from the rolling element. Also, an upper end of the bearing portion always abuts the lower rail.
When the upper rail slides in the second direction, a force in the first direction is applied from the upper rail to the bearing portion. As a result, the bearing portion slides in the first direction in the concave stepped portion. Thus, the bearing portion contacts the rolling element, and a rolling resistance of the rolling element is increased. Consequently, a resistance force when sliding the upper rail is increased.
In contrast, when the upper rail slides in the first direction, the bearing portion slides in the second direction in the concave stepped portion. Thus, the bearing portion recedes from the rolling element, and the rolling resistance of the rolling element is not increased. Consequently, the resistance force when sliding the upper rail is not increased.
According to the technique disclosed in Patent Document 1, therefore, when the upper rail slides in the second direction, the resistance force during sliding is great, whereas when the upper rail slides in the first direction, the resistance force during sliding is small.